One-step butyl alcohol process



Patented Aug. 14, 1951 ON E- STEP BUTYL ALCOHOL PROCESS Ralph C.Schreyer, New Castle, Del., assignor to E. I. du Pont de Nemours &Company, Wilmington, DeL, a corporation of Delaware No Drawing.Application July 24, 1948, Serial No. 40,622

.7 Claims.

This invention relates to improvements in the manufacture of n-butanoland isobutanol.

It has been disclosed heretofore that oxygencontaining organic compoundscan be prepared by reaction between olefines, carbon monoxide andhydrogen in the presence of hydrogenation catalysts at elevatedtemperatures and pressures (U. S. patents 2,327,066 and 2,437,600;copending applications S. N. 636,262, now Patent No. 2,526,742 filedDecember 20, 1945 and S. N. 677,922, now Patent No. 2,473,995 filed June19, 1946). It has also been disclosed (copending application S. N.598,209, filed June 7, 1945) that organic oxygen-containing compounds,including aldehydcs and compounds derivable therefrom, can be obtainedby reacting an organic compound containing olefinic unsaturation withcarbon monoxide and hydrogen under superatmospheric pressure at atemperature of 125 to 350 C. in the presence of a salt of cobalt ornickel, said salt being dissolved in the reaction mixture. In copendingapplication S. N. 636,263, filed December 20, 1945, it has beendisclosed that n-butanol and isobutanol can be prepared in good yield byreaction between propylene, CO, and H2 at temperatures of 250 to 400 C.under pressures exceeding 300 atmospheres, in the presence ofhydrogenation catalysts, the chief by-products being propane and certainesters; more particularly it has been found that butyl formate isproduced in substantial quantity (ca. 10% conversion) in this previouslydisclosed process for manufacturing butanols from propylene, CO and H2.

An object of this invention is to prepare nbutanol and isobutanol inimproved yield from propylene, CO and H2. Another object is to provideimprovements in the manufacture of butanols from propylene, CO and H2whereby excessive hydro enation of propylene, and convers on ofpropylene to ester (lrutyl formats), is avoided and an increased rate ofproduction of butanols is obtaned. Other objects of the invention appearhereinafter.

It has been discovered in accordance with this invention that n-butanoland isobutanol can be prepared in high yield by reaction betweenpropylene, CO and H2 at temperatures of 225 to 300 C. undersuperatmospheric pressures in the presence of a cobalt-containingcatalyst, preferably a cobalt-containing catalyst which is dissolvedin'at least one of the ingredients of the reaction mixture, andpreferably also in the presence of water. In a specific embodiment butylformate, which, it has been discovered, is produced in the reactionbetween propylene, CO

H and H2, is recovered and recycled to the reaction vessel. It has beendiscovered that by introducing about 10% to 15% of butyl formate (basedupon the weight of propylene) with the propylene and water no additionalbutyl formate is produced in the reaction between propylene, CO and H2at the said temperatures and pressures.

The butyl formate which is, in general, recovered and recycled in thepractice of the invention can be separated from the reaction product byany convenient method, preferably by distillation with Water, whichdistillation yields a heterogeneous ternary azeotrope containing butylformate, butanol and water. This azeotrope boils at a temperature ofabout to 84 C. and contains about 69 to 76 weight percent of ester, 7%to 10% of alcohols, and 17 to 21 of water.

Any cobalt-containing catalyst may be employed in the practice of theinvention. Cobalt salts of inorganic or organic acids are highlyeffective, e. g., cobalt chloride, cobalt sulfate, cobalt nitrate,cobalt acetate, cobalt propionate, cobalt isobutyrate, cobalt laurate,cobalt naphthenate, etc. It is desirable but not essential that thecobalt-containing catalyst employed in the practice of the invention beat least sparingly soluble in one of the ingredients of the reactionmixture, but insoluble catalysts, such as metallic cobalt or cobaltoxide may also be employed. Good results are obtained when thequantities of catalyst are as low as about 0.005% to about 5% based uponthe weight of cobalt per unit weight of propylene charged, but largeramounts of catalyst may of course be used. Small amounts of organic orinorganic acid may be present, if desired; best results are obtained ata pH below 7, in general. The addition of acid to the reaction mixture,however, is not necessary, excellent results being obtained in theabsence of added acid.

In specific embodfments it is frequently desirable to carry out thereaction between propylene, CO and H2 continuously in such a manner thatthe reaction zone ad acent to the exit portion of the reactor ismaintained at a higher temperature than the reaction zone adjacent tothe inlet portion of the reactor.

In the synthesis of butanols from propylene, CO and H2 in accordancewith this invention the reaction pressure should be relatively high,best results being obtained at pressures in the range of about 350 to1500 atmospheres or higher.

In general, it is desirable in the practice of the invention to employan excess of both hydrogen and carbon monoxide. The mole ratio of CO:H2may be varied, but it is generally preferred that 3 the mole ratio of:32 be initially from 3:1 to 1:3.

It has been discovered in accordance with the invention that water isnecessary for high conversion and high yield of butanols. For example,in the absence or water relatively low conversions i0% to 45%) andrelatively larger amounts of high boiling products (20% to 25%) wereobtained. These difficulties cannot be avoided by lowering the reactiontemperature, since at temperatures below about 225 C. substantialquantities of butyraldehydes are obtained.

Under the conditions described herein propylene is converted ton-butanol and isobutanol in yields exceeding about 80%, with completeconsumption of the propylene, the chief by-product being propane whichis produced to the extent of about of the propylene charged. The moleratio of n-butanol:isobutanol varies somewhat, and is frequently about 2:1.

The butanol which are produced in accordance with the invention may beseparated from the crude reaction product by any convenient and suitablemethod such as by direct distillation. If desired, the distillation canbe carried out at atmospheric pressure or under diminished pressure. Inthe embodiment in which a water-soluble co balt compound is employed ascatalyst the reaction product can be subjected to steam distiliation andthe aqueous portion of the distillation residue can be continuouslyrecycled to the reaction vessel.

If desired, gaseous or liquid diluents may be employed in addition tothe water which is required as a solvent, but in general these otherdiluents (e. g., benzene, dioxane, etc.) do not result in increasedconversion of propylene t butanols. The effect of water as a diluent isvery marked, however, as explained above. It is sometimes desirable tohave in the reaction mixture a small quantity of an inorganic or organicacid, which has a somewhat beneficial effect on the yield of butanols,in certain instances.

The invention is illustrated further by means of the following examples:

Example 1.A mixture containing 42 grams of propylene, 36 grams of water,grams of butyl formats and 1 gram of finely divided cobalt metal washeated in a silver-lined shaker tube of 325 cc. capacity with carbonmonoxide and hydrogen (mole ratio of COIHZ equals 1:1) at 249 to 255 C.for one hour under a pressure of 610 to 710 atmospheres. The resultingproduct was withdrawn from the reaction vessel and was freed of water byadmixing with chloroform and distilling water in the form of awater-chloroform azeotrope until a non-aqueous distillate was obtained.The chloroform was then removed by distillation and the residue wasdistilled yielding 58 grams of ma-- terial boiling in the range of 100to 117 C. This fraction containing 9.8 grams of butyl formats, theremainder of the fraction being n-butanol and isobutanol. A smalldistillation heel remained. The chief reaction product other thann-butanol and isobutanol was propane which was formed by directhydrogenation of the propylene which was initially presen in thereaction mixture.

Example 2.-A. mixture containing e2 grams of propylene, 18 grams ofwater, 1 gram of acetic acid and 1 gram of cobaltous acetate was heatedfor 1 hour with carbon monoxide and hydrogen (mole ratio of CO :Hzequals 1 :1) under a pressure of 690 to 705 atmospheres in a reactionvessel of 325 cc. capacity at a temperature of 245 to C. The entireliquid product was distilled yielding about 62.6 grams of butanols,which corresponds to a conversion of to based on the propylene initiallyintroduced. The chief byroducts were butyl formats and propane.

Example 3.A mixture containing 42 grams of propylene, 18 grams of Water,0.5 gram of sulfuric acid, 0.6 gram of acetic acid and 0.0 gram ofcobaltous sulfate was heated with carbon monoxide and hydrogen (moleratio of CO:H2 equals 1:1) for 30 minutes at a temperature of 168 to 204C., and thereafter for an additional 30 minutes at a temperature of 245to 250 C. The pressure during the first heating stage was 250 to 550atmospheres, and during the final heating stage was 650 to 700atmospheres. The liquid product which was withdrawn from the reactionvessel weighed 88.1 grams, which corresponds to a weight increase of26.1 grams (theory for complete conversion to butanols, 32 grams). Thegaseous product was passed through dry ice traps, but virtually nocondensate was formed, which indicated that there was very little, ifany, hydrogenation of propylene to propane. The liquid product wasdistilled and analyzed for ester content, the results indicating thatconversion to ester was only about 3 to 5 There was virtually no liquidreaction product boiling below 80 C. This ester could be separatedazeotropically (13.1 of azeotrope 80 to 84 C., containing 69% to 76% byweight of ester, 7% to 10% by weight of alcohols and 17% to 21% byweight of water) and recycled with propylene, water and catalyst asabove described, to produce butanols in very high yield.

It is to be understood that the foregoing examples are illustrative onlysince many embodiments or" the invention will occur to those who areskilled in the art. The process of the invention may be carried outeither batchwise or continuously. If desired, very short reaction timesmay be employed; in fact, flash reactions are frequently obtained, whichindicates that the reactants can be converted to butanols in an almost ainfinitesimally small reaction time if equipment limitations do notrequire a longer period in the reaction vessel. Relatively smallquantities of catalyst (less than 0.05% by weight calculated as cobaltmetal based on the propylene charged) may be employed withoutsubstantial decrease in rate of conversion, and in fact small quantitiesof catalyst (less than 1%) give some-what better results than quantitiesin excess of about 2% based on the weight of propylene charged.

Since many different ways of practicing the invention will occur tothose who are skilled in the art, it is to be understood that I do notlimit myself except as set forth in the following claims.

I claim:

1. A process for preparing butanols which comprises introducingpropylene, butyl formate, water, CO and H2 into a reaction vessel, andcarrying out the resulting reaction between the said propylene, CO andH2 under superatmospheric pressure at a temperature of 225 to 300 C. inthe presence of a cobalt-containing catalyst, whereby a reaction productcontaining n-butanol and isooutanol is obtained and the formation ofadditional amounts of butyl formate from propylene, CO and H2 issuppressed by the butyl formats which has been introduced, andthereafter recovering n-butanol and isobutanol from the resultingmixture.

2. A process for preparing butanols which comprises, reacting propylenewith CO and H2 under a pressure of 350 to 1500 atmospheres at atemperature of 225 to 300 C. in the presence of Water and a compound ofcobalt dissolved in at least one of the ingredients of the reactionmixture whereby a reaction product containing nbutanol, isobutanol andbutyl formate is obtained, recovering the said butyl formate, recyclingthe said butyl formate to the reaction vessel and thereafter recoveringn-butanol and isobutanol from the resulting mixture.

3. The process of claim 2 in which the said catalyst is cobalt acetate.

4. The process of claim 2 in which the initial mole ratio of CO-zI-h isfrom 3:1 to 1:3 inclusive.

5. The process of claim 2 in which the quantity of catalyst employed is0.001% to 2.0% of the weight of propylene present initially.

6. In the process of making n-butanol and isobutanol from propylene, COand hydrogen in the presence of a cobalt-containing catalyst, the stepwhich comprises recovering butyl formate from the reaction product andrecirculating the said butyl formate to the reaction vessel, whereby theREFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,327,066 Roelen Aug. 17, 19432,403,524 Hagemann July 9, 1946 2,418,899 Pevere et al Apr. 15, 1947OTHER REFERENCES Fiat Final Report No. 1000 PB-81383, December 26, 1947,pages 23 and 32.

Serial No. 373,703, Martin (A. P. C.), published July 13, 1943.

1. A PROCESS FOR PREPARING BYTANOLS WHICH COMPRISES INTRODUCINGPROPYLENE, BUTYL FORMATE, WATER CO AND H2 INTO A REACTION VESSEL, ANDCARRYING OUT THE RESULTING REACTION BETWEEN THE SAID PROPYLENE, CO ANDH2 UNDER SUPERATMOSPHERIC PRESSURE AT A TEMPERATURE OF 225* TO 500* C.IN THE PRESENCE OF A COBALT-CONTAINING CATALYST, WHEREBY A REACTIONPRODUCT CONTAINING N-BUTANOL AND ISOBUTANOL IS OBTAINED AND THEFORMATION OF ADDITIONAL AMOUNTS OF BUTYL FORMATE FROM PROPYLENE, CO ANDH2 IS SUPPRESSED BY THE FORMATE PROPYLENE, WHICH HAS BEEN INTRODUCED,AND THEREAFTER RECOVERING N-BUTANOL AND ISOBUTANOL FROM THE RESULTINGMIXTURE.